Chemical composition of essential oils of Drimys angustifolia Miers and Drimys brasiliensis Miers and their repellency to drywood termite Cryptotermes brevis (Isoptera: Kalotermitidae)
the essential oils extracted from leaves of the southern Brazilian native species Drimys angustifolia Miers (DA) and Drimys brasiliensis Miers (DB) by Clevenger distillation were analyzed by gas chromatography/ mass spectrometry (GC/Ms). the oils of DA and DB consisted predominantly of monoterpenoids and sesquiterpenoids. the largest components of DA oil were bicyclogermacrene (19.6%), sabinene (9.7%) and myrcene (5.2%), while DB oil was characterized by cyclocolorenone (18.2%), followed by terpinen-4- ol (8.7%) and alpha-gurjunene (6.9%). Laboratory tests were carried out to determine the repellency of the essential oils to the drywood termite Cryptotermes brevis (Isoptera: Kalotermitidae). It was observed that the oil showed repellency at the concentrations 25, 12.5, and 6.25 μg/mL. The oils of both species exhibited a negative repellency index, which represents repellent activity, except for DA oil at the highest concentration, which was attractive. Five deaths (11% of the termite sample) were observed at 25 μg/mL DA, in the fourhour repellency test, while four deaths occurred at 12.5 μg/mL (approximately 9%). The essential oil of DB did not cause any termite deaths.